Pressure control valve assembly and method of calibration

ABSTRACT

In preferred form, a pressure control valve assembly including a hollow cylindrical housing having an open end and a closed end formed by a conical member including a centrally located inlet port therein, the open end of the cylindrical member is closed by a sheet metal spring retainer having a continuously formed relatively rigid peripheral flange thereon joined by a continuously formed surface inclined downwardly into the interior of the hollow cylindrical housing to a centrally located inverted cup formation located coaxially of the inlet port. The cup formation is plastically deformable relative to the peripheral flange to set a relief pressure of a ball check element held against the inlet port by a spring element carried by the cup formation.

United States Patent [72] Inventor James M. Shea 3,396,449 8/1968Brantner 73/4X S i Mi h, 3,471,087 10/1969 Caparone et al l37/505.41X [3PP 820,947 Primary Examiner-Robert G. Nilson gg e ted gg gg Attorneys-W.E. Finken and J. C. Evans n [73] Assignee General Motors CorporationDetroit, Mich.

a corporation of Delaware [54] PRESSURE CONTROL VALVE ASSEMBLY ANDABSTRaCT: In preferred form, a pressure control valve as- METHOD OFCALIBRATION sembly mcludmg a hollow cylindrical housing having an open 6Claims 5 Drawing Figs end and a closed end formed by a conical memberincluding a centrally located inlet port therein, the open end of thecylin- [52] US. Cl 137/5221: drical member is closed by a sheet metalspring retainer ing a continuously formed relatively rigid peripheralflange [51] Illt. Cl Flfik 15/00 thereon joined by a continuously formedSurface inclined [50] Fleld of Search l37z/539, downwardly into theinterior of the hollow cylindrical housing SOS-41pm 73/ 4 to a centrallylocated inverted cup formation located coaxially of the inlet port. Thecup formation is plastically deformable [56] References cued relative tothe peripheral flange to set a relief pressure of a ball UNITED STATESPATENTS check element held against the inlet port by a spring element1,177,831 4/l9l6 Taylor et al l37/539X carried by the cup formation.

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e% l X V i H l I g 74 fi I t 7y 76' [a i? PATENTED JAN 1 215m[NV/.iN'TOR. (fame: Z/Zfeo A r TORNEY PRESSURE CONTROL VALVE ASSEMBLYAND METHOD OF CALIBRATION This invention relates to pressure controlrelief valve assemblies and more particularly to such assembliesincluding a spring-biased ball check element for maintaining apredetermined relief point and including a method for calibrating suchassemblies. I In pressure control relief valve assemblies it isdesirable to maintain a relief control point by means of a minimumnumber of parts preferably including a single valve element and a springmember for maintaining the ball element seated in-closed position untila predetermined pressure occurs, at which time the ball element islifted form an inlet port or the like to allow relief flow of fluidthrough the assembly.

Also, the assembly should be easily assembled and calibrated.

An object of the present invention is to provide a relief valve assemblyhaving a minimum of working component parts and means to readilycalibrate the assembly at an exact pressure relief control point. r

A further object of the inventionis to provide such an assembly whereinthe unit is calibrated by plastically deforming a sheet metal springretaining component of the assembly with respect to a more rigid housingportion thereof to apply an exact spring force on avalving element ofthe assembly which force determines the point at which the assemblyallows relief fluid flow therethrough. t

Still another object of the present invention is to simplify calibrationof a relief valve assembly of the type including a hollow housing havingan open end and a'closed' end in which is located a valved inlet port bythe provision of a sheet metal spring retainer accessible through theopen end of thehousing to be plastieally deformed to adjust the springforce on a ball check element thereby to'set the relief pressure of theassembly. i Y

Still another object of the present invention is to calibrate pressurecontrol relief valve assemblies by a method including the steps of:locating a retainer having arigid segment thereon and a flexible segmentthereon within the hollow interior ofa relief valve housing of the typeincluding an inlet port closed by a ball check element which is held inplace by a spring element seated on the flexible segment of the springretainer; biasing the ball check to open when a slight, pressure differential occurs thereacross; opening the ball'check valve by directingfluid flow thereacross at a low pressure; actuating a pressure ram inresponse to thelo'w pressure to deform the flexible segment of theretainer in a manner to increase the spring force' acting on the ballcheck to cause an increase in the pressure differential required to openthe ball check valve; and terminating deformation of the flexiblesegment of the retainer when spring force is increased .on the ballelement to produce a desired predetermined pressure relief point for theoperation of the assembly.

In the preferred embodiment of the invention these and other objects areattained by means of a valve assembly including a hollow cylindricalhousing having an open end and a closed end. An inlet port in the closedend has a ball element seated thereon and maintained thereagainst by acoil spring that extends into the interior of the housing centrallythereof.

The open end of the housing is closed by a sheet metal spring retainerthat includes a continuously formed radiallyoutwardly directedreinforcing flange thereon fixedly secured to the valve housing andjoined to a'more flexible central segment of the retainer whichsupportingly receives the opposite end of the coil spring. The centralsegment is deformed with respect to the spring to set the spring forceon the ball element and thereby determine the pressure relief point ofassembly.

The calibration method is accomplished by means of a positivedisplacement pump directing an incompressible fluid through the inletport against the spring biased ball check valve element. Initially thespring retainer is located with respect to the housing so that the-ballcheck is easily opened. The low pressure differential requiredto' openthe ball-check initially is sensed and means are included to cause ahydraulic ram to deflect the flexible portion of the retainer upon, theoccurence of such low pressure flow through the inlet port thereby toincrease the spring force acting on the ball element. Eventually thedeformation issufficient to cause a spring force on the ball elementthat will result in a pressure differential to open the ball elementequal to a desired set control point for relief. At this point the unitis calibrated.

The above and other objects and advantages will be made more apparentfrom the following specification taken in conjunction with theaccompanying .drawings wherein like reference numerals refer to likeparts and wherein:

FIG. 1 is a view in perspective, partially broken away, showing thepressure control valve assembly of the present invention in associationwith a reciprocating pump unit;

FIG. 2 is an enlarged vertical sectional view of the pressure controlvalve assembly of the present invention before a spring retainer issecured therein;

FIG. 3 is a top elevational view of the pressure control valve assemblyof the present invention;

FIG. 4 is a diagrammatic view of a fluid circuit used in the method ofcalibration of the present invention; and

FIG. 5 is an enlarged cross-sectional view of the valve of the presentinvention in place in the calibrating device of FIG. 4.

Referring now to FIG. 1, a pump unit 10 is illustrated that includes ahousing 12 having a pump bore 14 directed through the upper part thereofwhich communicates at its lower end with a chamber 16 in which islocated a cam operator 18 which reciprocates a piston 20 in the bore 14.The piston carries an O-ring seal 21 in its outer periphery. In theillustrated arrangement the housing 12 includes mounting brackets 22,23.

The cam 18 is connected to a shaft 24 that has a threaded end connectedby means including a nut 25 to an operating lever 26 moves arcuately upand down so as to oscillate the shaft 24 and connected cam 18 about theaxis of the shaft 24.

The piston 20 is thereby reciprocated within the bore 14 to produce anintake stroke wherein fluid flows from the chamber 16 through a centralpassageway 28 within the piston 20 and across the ball check element 30into a variable volume chamber 32 defined in the bore 14 between thepiston 20 and a relief valve assembly 34 constructed in accordance withprinciplesof the present invention. During a discharge stroke the piston20 is moved upwardly within the bore 14 so as to reduce the volume ofthe chamber 32 and fluid is discharged therefrom through an outlet 33across a spring biased check valve 35.

Under certain circumstances the relief valve assembly 34 will open tocommunicate the variable volume chamber 32 with a low pressure reservoir36 formed by an inverted, open ended cam 38 on the upper end of thehousing 12. More particularly, the cam 38 is sealed with respect to thehousing 12 by means of an O-ring seal element 40 that is seated withinan annular opening in an upwardly directed flange 42 of the housing 12which defines a shoulder 44 on which the bottom edge of the inverted cam38 is supportingly received.

The above-mentioned component parts of the reciprocating pumparrangement form no part of the present invention and are onlyillustrated as being representative of one suitable system in which thepressure control valve assembly of the present invention might beincluded.

For a more detailed explanation of the reciprocating pump and itsassociated vehicle leveling system reference may be had to copendingapplication to Scott et al. Ser. No. 763,834 filed Sept. 30, 1968. 1Referring now moreparticularly to the relief valve assembly 34 asillustrated in FlGS. 1-3, it includes a hollow cylindrical housingmember 46 open at its upper end and closed at its opposite end by agenerally conically shaped base portion 48 in which is located adepending centrally located nose portion 50 through which an inletorifice or port 52 passes for communicating the interior 54 of thehousing member 46 with a fluid pressure source.

1n the illustrated arrangement, an annular inside located edge oftheport 52 defines a seat 56 that supportingly receives a ball checkelement 58 for closing the inlet port 52. A compression spring 60 islocated centrally of the interior 54 and coaxially with the inlet port52 and ball check element 58 More particularly. it has the lower endthereof in engagement with the ball check element 58 and the upper endthereof extending in the direction of the upper open end of the housingmember 46 to a point where it is supportingly received by an invertedcup-shaped formation 62 on a sheet metal spring retainer element 64located in the upper end of the housing member 46.

ln accordance with certain principles of the present invention, thespring retainer element 64 includes a radially outwardly locatedcontinuously formed circumferential flange 66 seated on an annularshoulder 68 on the upper end of the housing member 46. The flange 66 isfixedly secured with respect to the housing by means of a radiallyinwardly directed portion 70 of the housing member 46 that seats againstthe upper face of the flange 66 in the manner best illustrated in FIG. 1thereby to accurately maintain the inverted cup-shaped formation 62 inits coaxial alignment with the spring 60 and ball check element 58.

Moreover, the flange 66 is joined to the cup-shaped formation 62 by acontinuously formed truncated conical segment 72 of the element 64thatextends from the flange 66 inwardly and downwardly ofthe housinginterior 54.

As is best illustrated in F108. 2 and 3, the element 64 includes aplurality of circumferentially located openings 74 therein that arelocated in the segment 72 between the flange 66 and the invertedcup-shaped formation 62. More particularly, in the illustratedarrangement, the openings 74 are formed by pierce forming a plurality oftabs or cars 76 from the segment 72. The tabs 76 depend downwardly fromthe cup-shaped formation to define a cage surrounding a substantiallength of the compression spring 16 so as to maintain it in its coaxialalignment with the ball check element and inlet port 52. In addition tothis function the openings 74 left by the tab formation define a passagefor relieved liquid or gas through the housing member 46. They alsoweaken the retainer to allow deformation of formation 62 with respect toflange 66 to set a reliefpoint.

In one working embodiment the retainer element 64 was drawn from 22 gagesteel stock, SAE 1008-1010 and had the following dimensionalcharacteristics.

Inches Hi:IIIIIIIIIIIIIIIIIIIIIIIIIIIII 115 1 Approximately.

By virtue of the above arrangement, the retainer element has asubstantially greater flexibility at the center thereof as compared tothe flexibility or rigidity in the portion of the element represented bythe segment 72 and flange 66. Thus, the cup-shaped formation can beplastically deformed inwardly of the interior 54 to reduce the distancebetween the spring engaging portion of the element 64 and the ball checkelement 58. This produces a reduction in the length of the compressionspring 60 and a resultant increase in the spring biasing force on theball check element 58 required to lift it from its seat defined by theedge 56 thereby to control the release set point of the assembly 34. i

In accordance with other features of the present invention, the openings74 that enable the spring engaging cup-shaped formation to be readilyplastically deformed with respect to the remainder of the element 64further serves as an o utlet opening from the interior 54 to a lowpressure source, for example, the low pressure reservoir 36 in theenvironment representatively illustrated in FIG. 1.

Element Rating Housing 46 .0897 inches SAE 1008-10 steel. Ball checkelement 58 .1563 inches SAE 50100 steel. Orifice 2 .134/139 inches. Seat56 Burnished.

{.25 means dgllamfteiii te S rln 60 140 poun per nc ra p g 18.2 poundsinstalled load.

The enumerated characteristics of these component parts are merelyrepresentative of one working embodiment it being understood thatvariations as to dimensions, materials and spring ratings will occurdepending upon the application in which the valve is used and the reliefcharacteristics that are desired under such application.

In accordance with the invention, the aforedescribed parts can beassembled and accurately calibrated by a unique calibration method, tobe discussed, without need to compensate for commercial springtolerances and tolerance stack up of the component parts of theassembly.

More particularly, the method contemplates the following steps.

First, the ball check element 58, the coil spring 60 and retainer 64 arecoaxially aligned within the housing member 46 as is illustrated in FIG.2. Then an upwardly directed lip that is the shape of the flange 70before it is directed radially inwardly as seen in FIG. 1, is spun overthe retainer.

The parts are configured so that the valve as assembled at this pointrelieves at a point below the specified relief pressure. This can beaccomplished well within the manufacturing tolerances of the componentparts.

Then as best seen in FIGS. 4 and 5, the valve assembly 34 is placed in amachine 78 for automatically setting the predetermined relief pressurepoint. i

More particularly, in the illustrated arrangement the machine 78 isdiagrammatically illustrated as including a base 80 including a steppedbore 82 in which is located the housing member 46. The bore 82 iscommunicated with a passageway 84 to an inlet conduit 86 connected to apressure monitored supply system 88.

The machine further includes a head 90 sealed with respect to base 80 bya seal element 9]. Head 90 has a bore 92 therein in which is located ahydraulic ram 94. The ram 94 carries an annular O-ring 96 whichseparates a variable volume space 98 on the upper end of the ram 94 fromthe underside thereof as illustrated in FIG. 5. The underside of the ramis representatively illustrative as including a depending segment 99thereon that engages the upper surface of the cup-shaped formation 62for purposes to be discussed.

The head 90 includes a passageway 100 that communicates the interior 54of the assembly 34 with a return conduit 102 back to a fluid reservoir104.

The system 88 further includes an intake pipe 106 from the reservoir 104to the inlet of a positive displacement pump 108 that has its outletconnected through a discharge pipe 110 to the supply conduit 86.

The pressure on the discharge of the pump 108 is indicated by a pressuresensor 112 which produces a signal for controlling fiuid flow through apressure control valve 114 that is connected to the outlet of a positivedisplacement pump 116. An intake conduit 118 connects a reservoir 120 tothe inlet of pump 116. When the pressure sensor 112 detects alow-pressure signal it will cause the pressure control valve 114 to opento direct high-pressure hydraulic fluid through a supply conduit 122into the variable volume chamber 98 above the ram 94,

" wardly of the valve seat and bypass fluid back'throughtheintcrior 54and the return passageway 100, return conduit 102, back tothe reservoir104. The sensor 112 detects a smallpres- .sure buildup and as aresultthe flow control valve 114 is opened to allow highpressurehydraulic fluid to'flow through the supply'conduit 122 tothe variablevolume high pressure chamber 98. This causes the ram 94 tomovedownwardly and the depending segment 99 thereon tobear againstthecupshaped formation :62. so as to cause a plastic (deformationtherein. Concurrently thelength of the compression spring is reduced anda resultant increase in the spring force on thetball v element 58occurs.

There is a commensurate increase of pressure differential across theball ch'eck element 58 that causes the pressure'sensor .112 toprogressively detect a larger and larger pressurein the supply conduit86. Eventually a desired predetermined pressure control point is reachedat which the assembly 34-is supposed to operate. At this time, thesensor and flow. control valve 114 will coact to terminate fluid flowfromthe pump 116. to the variable volume chamber 98and the assembly 34willbe removed from the machine 78;

The degree of plastic deformation of the element 64 at thecentralportion thereof will be adequate to compensate for any tendencies for aslightmetal-spring back of theinverted cupshaped formation 62 followingthe calibration step andas a result an exact setting can beobtained forevery valve. as sembly located in and calibrated by the machine inzacacordance with the method of the present invention.

The embodiments of the inventions described hereinare for purposes ofillustration and. the scope of the inventions are in tended to belimited only by the following claims.

lclaim:

l. A relief valve assemblycompri sing a housing having a hollowcylindrical portion and a base portion, an openingin said base portion,a ball check elementseated on said base portion interiorly thereof andinoverlying relationship to. said opening therethrough, aspring retainerinsaid. hollow cylindrical portion including a radially outwardlydirected flange; thereon, means securing said flange to said cylindricalportion to fix said retainer with respect thereto, said retainer furtherincluding a centrally located inverted cup portionuarranged coaxially ofsaid valve opening, a plurality of tabs depending from said cup portiondefining a cage below saidinverted cup, a spring element having oneendthereof in engagementwith said ball check element andan opposite endportion thereon an opposite endportion thereon seated'within saidinverted cupportion for biasing said ball check element against saidcoilspring having one endthereof seated on saidball'element andtheopposite end thereof extending centrally through said cylindricalhousing, a springr'etairier located within said housing including. acontinuously formed radially outwardly directed peripheral flangethereon and a centrally locatedinvertedcup-shaped portion thereonreceiving' the opposite end ofsaidcoil-spring;means on said'housing forfixedly supporting-the radially outwardly directed-flangeon'theretainer; said retainer including, a plurality .of openingsthereinlocatedcircumferentially around said central invertedcup-shapedportion between it'and. said continuously formed radiallyoutwardly directed flangeto allowplastic deformation of said retainer tocause said.cup.-shaped portion to shift axially inwardly of .saidhousing in the .direction'of said base portion thereof iwhen a force-isapplied to said inverted cup-shaped portion-thereby-tocontrolthe springforce'acting on said ball element,saidcontinuously formedradiallyoutwardly directed flange on saidretainer maintaining a coaxialalignment of said invertedcup shaped portion and said ball elementduring-the before described plastic deformation of said retainer.

4. A relief valveassemblyhcomprisingrarhollow cylindrical housing'having an open end and .a base segment, a port through saidbasesegment,a ball element closing said port, a t

seated within said inverted cup portion for biasing said ball checkelement against said closedend portion to close said openingtherethroughand. establish a relief pressure control point, saidcage-forming tab elements surroundingsaidspring element to maintain itin axial alignment withsaidcheck element, said retainer including aplurality of openings therein located outwardly of each of saiddepending tabsfor flow of fluid through said housing, said openingsallowing said in-. verted cup portion to be axially deflectedinwardly ofsaid cylindrical portion in the direction of said base portion to setthe pressure point at which said ball element will .lift'from said baseportion opening.

2. A relief valve assembly comprising a housing having .a

hollow cylindrical portion and a base portion, an opening in said baseportion, a balllcheck element seatedon-said base portion interiorlythereof and in overlying relationship to said openingtherethrough, aspring retainer in said hollow cylindrical portion including a radiallyoutwardly directed flange thereon. means securing said flange to saidcylindrical portion to fix said retainer with respect thereto, saidretainer further including a centrally locatedinverted cup portionarranged coaxially of said valve opening, a spring element having oneend thereof in engagement with said ball check element and coil springhaving one end thereof seated on said ball element andthe oppositeuendthereof extending centrally through said cylindrical housing, aspring retainer located WithiflzSflld-hOUS- ing including a.continuously formed radially outwardly directed peripheral flangethereonand a centrally locatedin verted cup-shaped portion-thereonreceiving the oppositeend ofisaid .coilspring, said. housing includingan upwardly facing shoulder. supportingly receiving the. radiallyoutwardly directed flange on saidretainer, said housing furtherincluding aflange directed radially inwardly thereof and overlying saidretainer flange for fixedly securing it with respect to the said housingand to align said inverted cup-shaped portion thereon I coaxially withsaid spring and said ball element, saidretainer includinga plurality ofcircumferentially spaced depending. tabs thereon forming a cage aroundsaid spring for-maintain: ing said spring in axialialignment with said.ball elementysaid retainer including a plurality of openings thereinlocated cir-' cumferentially around .said central invertedcup-shapeduportion between it-and said continuously formedradiallyvoutwardlydirectedflange to allowplastic deformation ofsaidai retainer tocause saidcup-shaped portion to. shiftaxially. .inwardly of said housingin the ,directionof said base. portion thereof .when aforce is appliedto said inverted cup-shaped portion thereby to control the spring forceacting on said-ball .:i element, said continuously formed radiallyoutwardly directed l flange on said retainer maintaining a coaxialalignment'of said inverted cup-shaped portion and said ball elementduring the before described plastic deformation of said retainer.

5. A method for calibrating .a relief valve assembly of-the. type havinga housing with a valve opening into the interior of g the housing andwherein the valve opening is closed by a :ball check element maintainedagainst a valve seat in surrounding relationship tothe valve opening bymeans of a relief valve spring, comprising the steps of: placing theball check element I and valve spring within the interior of the housingin overlyingv relationship to the valve opening therethrough, 5 forming.a spring retainer element to have a radially outwardly directed flangethereon and a centrally located inverted cup portion therein surroundedby a plurality of openings to allow relative yicldahle movement betweensaid inverted cup-shaped portion and the radially outwardly directedflange thereon, fixedly securing the retainer element in one end of saidhousing to receive one end of the valve spring when the opposite endthereof is seated on the ball check element for holding it in a looselyseated position with respect to the valve opening, directing fluid flowthrough the opening plastically deforming the retainer and concurrentlycompressing the spring between the retainer cup portion and the ballelement to increase the spring force on the ball element thereby toproduce a predetermined pressure differential across the ball checkelement, and thereafter terminating further deforming of the retainerand said fluid flow through the valve opening.

6. A method for calibrating a valve assembly of the type including ahousing having a hollow interior with an inlet port thereto and anoutlet opening therefrom and wherein the inlet port is closed by meansof a ball element and spring member located within the interior of thehousing, comprising the steps of: locating a sheet metal retainer withinthe housing including a relatively rigid segment thereon fixedly securedto the housing and a yieldable segment thereon located in alignment withthe ball element and spring for holding the spring in place against theball element to close the inlet port against flow at a low pressure,directing a first predetermined fluid flow at a first predeterminedpressure through said inlet port to lift the ball element, applying aforce against the yieldable retainer segment in accordance with thefirst predetermined pressure to increase the spring force on the ballelement by deforming the yieldable segment with respect to therelatively or rigid segment so as to increase the pressure differentialacross the ball element, sensing a resultant pressure increase of fluidflowing through inlet port and terminating deformation of the yieldablesegment of said retainer when a predetermined pressure increase occurs.

1. A relief valve assembly comprising a housing having a hollowcylindrical portion and a base portion, an opening in said base portion,a ball check element seated on said base portion interiorly thereof andin overlying relationship to said opening therethrough, a springretainer in said hollow cylindrical portion including a radiallyoutwardly directed flange thereon, means securing said flange to saidcylindrical portion to fix said retainer with respect thereto, saidretainer further including a centrally located inverted cup portionarranged coaxially of said valve opening, a plurality of tabs dependingfrom said cup portion defining a cage below said inverted cup, a springelement having one end thereof in engagement with said ball checkelement and an opposite end portion thereon seated within said invertedcup portion for biasing said ball check element against said closed endportion to close said opening therethrough and establish a reliefpressure control point, said cage-forming tab elements surrounding saidspring element to maintain it in axial alignment with said checkelement, said retainer including a plurality of openings therein locatedoutwardly of each of said depending tabs for flow of fluid through saidhousing, said openings allowing said inverted cup portion to be axiallydeflected inwardly of said cylindrical portion in the direction of saidbase portion to set the pressure point at which said ball element willlift from said base portion opening.
 2. A relief valve assemblycomprising a housing having a hollow cylindrical portion and a baseportion, an opening in said base portion, a ball check element seated onsaid base portion interiorly thereof and in overlying relationship tosaid opening therethrough, a spring retainer in said hollow cylindricalportion including a radially outwardly directed flange thereon, meanssecuring said flange to said cylindrical portion to fix said retainerwith respect thereto, said retainer further including a centrallylocated inverted cup portion arranged coaxially of said valve opening, aspring element having one end thereof in engagement with said ball checkelement and an opposite end portion thereon seated within said invertedcup portion for biasing said ball check element against said closed endportion to close said opening therethrough and establish a reliefpressure control point, said retainer including a plurality of openingstherein located outwardly of said cup portion for flow of fluid throughsaid housing, said openings allowing said inverted cup portion to beaxially deflected inwardly of said cylindrical portion in the directionof said base portion to set the pressure point at which the ball elementwill lift from the base portion opening.
 3. A relief valve assemblycomprising a hollow cylindrical housing having an open end and a basesegment, a port through said base segment, a ball element closing saidport, a coil spring having one end thereof seated on said ball elementand the opposite end thereof extending centrally through saidcylindrical housing, a spring retainer located within said housingincluding a continuously formed radially outwardly directed peripheralflange thereon and a centrally located inverted cup-shaped portionthereon receiving the opposite end of said coil spring, means on saidhousing for fixedly supporting the radially outwardly directed flange onthe retainer, said retainer including a plurality of openings thereinlocated circumferentially around said central inverted cup-shapedportion between it and said continuously formed radially outwardlydirected flange to allow plastic deformation of said retainer to causesaid cup-shaped portion to shift axially inwardly of said housing in thedirection of said base portion thereof when a force is applied to saidinverted cup-shaped portion thereby to control the spring force actingon said ball element, said continuously formed radially outwardlydirected flange on said retainer maintaining a coaxial alignment of saidinverted cup shaped portion and said ball element during the beforedescribed plastic deformation of said retainer.
 4. A relief valveassembly comprising a hollow cylindrical housing having an open end anda base segment, a port through said base segment, a ball element closingsaid port, a coil spring having one end thereof seated on said ballelement and the opposite end thereof extending centrally through saidcylindrical housing, a spring retainer located within said housingincluding a continuously formed radially outwardly directed peripheralflange thereon and a centrally located inverted cup-shaped portionthereon receiving the opposite end of said coil spring, said housingincluding an upwardly facing shoulder supportingly receiving theradially outwardly directed flange on said retainer, said housingfurther including a flange directed radially inwardly thereof andoverlying said retainer flange for fixedly securing it with respect tothe said housing and to align said inverted cup-shaped portion thereoncoaxially with said spring and said ball element, said retainerincluding a plurality of circumferentially spaced depending tabs thereonforming a cage around said spring for maintaining said spriNg in axialalignment with said ball element, said retainer including a plurality ofopenings therein located circumferentially around said central invertedcup-shaped portion between it and said continuously formed radiallyoutwardly directed flange to allow plastic deformation of said retainerto cause said cup-shaped portion to shift axially inwardly of saidhousing in the direction of said base portion thereof when a force isapplied to said inverted cup-shaped portion thereby to control thespring force acting on said ball element, said continuously formedradially outwardly directed flange on said retainer maintaining acoaxial alignment of said inverted cup-shaped portion and said ballelement during the before described plastic deformation of saidretainer.
 5. A method for calibrating a relief valve assembly of thetype having a housing with a valve opening into the interior of thehousing and wherein the valve opening is closed by a ball check elementmaintained against a valve seat in surrounding relationship to the valveopening by means of a relief valve spring, comprising the steps of:placing the ball check element and valve spring within the interior ofthe housing in overlying relationship to the valve opening therethrough,forming a spring retainer element to have a radially outwardly directedflange thereon and a centrally located inverted cup portion thereinsurrounded by a plurality of openings to allow relative yieldablemovement between said inverted cup-shaped portion and the radiallyoutwardly directed flange thereon, fixedly securing the retainer elementin one end of said housing to receive one end of the valve spring whenthe opposite end thereof is seated on the ball check element for holdingit in a loosely seated position with respect to the valve opening,directing fluid flow through the opening plastically deforming theretainer and concurrently compressing the spring between the retainercup portion and the ball element to increase the spring force on theball element thereby to produce a predetermined pressure differentialacross the ball check element, and thereafter terminating furtherdeforming of the retainer and said fluid flow through the valve opening.6. A method for calibrating a valve assembly of the type including ahousing having a hollow interior with an inlet port thereto and anoutlet opening therefrom and wherein the inlet port is closed by meansof a ball element and spring member located within the interior of thehousing, comprising the steps of: locating a sheet metal retainer withinthe housing including a relatively rigid segment thereon fixedly securedto the housing and a yieldable segment thereon located in alignment withthe ball element and spring for holding the spring in place against theball element to close the inlet port against flow at a low pressure,directing a first predetermined fluid flow at a first predeterminedpressure through said inlet port to lift the ball element, applying aforce against the yieldable retainer segment in accordance with thefirst predetermined pressure to increase the spring force on the ballelement by deforming the yieldable segment with respect to therelatively or rigid segment so as to increase the pressure differentialacross the ball element, sensing a resultant pressure increase of fluidflowing through inlet port and terminating deformation of the yieldablesegment of said retainer when a predetermined pressure increase occurs.